[PATCH v3 00/19] Make git-pull a builtin

@@ -212,6 +212,13 @@ There are some macros to easily define options:
 	Use it to hide deprecated options that are still to be recognized
 	and ignored silently.
 
+`OPT_PASSTHRU(short, long, &char_var, arg_str, description, flags)`::
+	Introduce an option that will be reconstructed into a char* string,
+	which must be initialized to NULL. This is useful when you need to
+	pass the command-line option to another command. Any previous value
+	will be overwritten, so this should only be used for options where
+	the last one specified on the command line wins.
+
 
 The last element of the array must be `OPT_END()`.
 

@@ -134,3 +134,52 @@ int parse_opt_noop_cb(const struct option *opt, const char *arg, int unset)
 {
 	return 0;
 }
+
+/**
+ * Recreates the command-line option in the strbuf.
+ */
+static int recreate_opt(struct strbuf *sb, const struct option *opt,
+		const char *arg, int unset)
+{
+	strbuf_reset(sb);
+
+	if (opt->long_name) {
+		strbuf_addstr(sb, unset ? "--no-" : "--");
+		strbuf_addstr(sb, opt->long_name);
+		if (arg) {
+			strbuf_addch(sb, '=');
+			strbuf_addstr(sb, arg);
+		}
+	} else if (opt->short_name && !unset) {
+		strbuf_addch(sb, '-');
+		strbuf_addch(sb, opt->short_name);
+		if (arg)
+			strbuf_addstr(sb, arg);
+	} else
+		return -1;
+
+	return 0;
+}
+
+/**
+ * For an option opt, recreates the command-line option in opt->value which
+ * must be an char* initialized to NULL. This is useful when we need to pass
+ * the command-line option to another command. Since any previous value will be
+ * overwritten, this callback should only be used for options where the last
+ * one wins.
+ */
+int parse_opt_passthru(const struct option *opt, const char *arg, int unset)
+{
+	static struct strbuf sb = STRBUF_INIT;
+	char **opt_value = opt->value;
+
+	if (recreate_opt(&sb, opt, arg, unset) < 0)
+		return -1;
+
+	if (*opt_value)
+		free(*opt_value);
+
+	*opt_value = strbuf_detach(&sb, NULL);
+
+	return 0;
+}

@@ -224,6 +224,7 @@ extern int parse_opt_with_commit(const struct option *, const char *, int);
 extern int parse_opt_tertiary(const struct option *, const char *, int);
 extern int parse_opt_string_list(const struct option *, const char *, int);
 extern int parse_opt_noop_cb(const struct option *, const char *, int);
+extern int parse_opt_passthru(const struct option *, const char *, int);
 
 #define OPT__VERBOSE(var, h)  OPT_COUNTUP('v', "verbose", (var), (h))
 #define OPT__QUIET(var, h)    OPT_COUNTUP('q', "quiet",   (var), (h))

@@ -242,5 +243,7 @@ extern int parse_opt_noop_cb(const struct option *, const char *, int);
 	OPT_COLOR_FLAG(0, "color", (var), (h))
 #define OPT_COLUMN(s, l, v, h) \
 	{ OPTION_CALLBACK, (s), (l), (v), N_("style"), (h), PARSE_OPT_OPTARG, parseopt_column_callback }
+#define OPT_PASSTHRU(s, l, v, a, h, f) \
+	{ OPTION_CALLBACK, (s), (l), (v), (a), (h), (f), parse_opt_passthru }
 
 #endif

@@ -219,6 +219,12 @@ There are some macros to easily define options:
 	will be overwritten, so this should only be used for options where
 	the last one specified on the command line wins.
 
+`OPT_PASSTHRU_ARGV(short, long, &argv_array_var, arg_str, description, flags)`::
+	Introduce an option where all instances of it on the command-line will
+	be reconstructed into an argv_array. This is useful when you need to
+	pass the command-line option, which can be specified multiple times,
+	to another command.
+
 
 The last element of the array must be `OPT_END()`.
 

@@ -4,6 +4,7 @@
 #include "commit.h"
 #include "color.h"
 #include "string-list.h"
+#include "argv-array.h"
 
 /*----- some often used options -----*/
 

@@ -183,3 +184,22 @@ int parse_opt_passthru(const struct option *opt, const char *arg, int unset)
 
 	return 0;
 }
+
+/**
+ * For an option opt, recreate the command-line option, appending it to
+ * opt->value which must be a argv_array. This is useful when we need to pass
+ * the command-line option, which can be specified multiple times, to another
+ * command.
+ */
+int parse_opt_passthru_argv(const struct option *opt, const char *arg, int unset)
+{
+	static struct strbuf sb = STRBUF_INIT;
+	struct argv_array *opt_value = opt->value;
+
+	if (recreate_opt(&sb, opt, arg, unset) < 0)
+		return -1;
+
+	argv_array_push(opt_value, sb.buf);
+
+	return 0;
+}

@@ -225,6 +225,7 @@ extern int parse_opt_tertiary(const struct option *, const char *, int);
 extern int parse_opt_string_list(const struct option *, const char *, int);
 extern int parse_opt_noop_cb(const struct option *, const char *, int);
 extern int parse_opt_passthru(const struct option *, const char *, int);
+extern int parse_opt_passthru_argv(const struct option *, const char *, int);
 
 #define OPT__VERBOSE(var, h)  OPT_COUNTUP('v', "verbose", (var), (h))
 #define OPT__QUIET(var, h)    OPT_COUNTUP('q', "quiet",   (var), (h))

@@ -245,5 +246,7 @@ extern int parse_opt_passthru(const struct option *, const char *, int);
 	{ OPTION_CALLBACK, (s), (l), (v), N_("style"), (h), PARSE_OPT_OPTARG, parseopt_column_callback }
 #define OPT_PASSTHRU(s, l, v, a, h, f) \
 	{ OPTION_CALLBACK, (s), (l), (v), (a), (h), (f), parse_opt_passthru }
+#define OPT_PASSTHRU_ARGV(s, l, v, a, h, f) \
+	{ OPTION_CALLBACK, (s), (l), (v), (a), (h), (f), parse_opt_passthru_argv }
 
 #endif

@@ -46,6 +46,9 @@ Functions
 	Format a string and push it onto the end of the array. This is a
 	convenience wrapper combining `strbuf_addf` and `argv_array_push`.
 
+`argv_array_pushv`::
+	Push a null-terminated array of strings onto the end of the array.
+
 `argv_array_pop`::
 	Remove the final element from the array. If there are no
 	elements in the array, do nothing.

@@ -49,6 +49,12 @@ void argv_array_pushl(struct argv_array *array, ...)
 	va_end(ap);
 }
 
+void argv_array_pushv(struct argv_array *array, const char **argv)
+{
+	for (; *argv; argv++)
+		argv_array_push(array, *argv);
+}
+
 void argv_array_pop(struct argv_array *array)
 {
 	if (!array->argc)

@@ -17,6 +17,7 @@ __attribute__((format (printf,2,3)))
 void argv_array_pushf(struct argv_array *, const char *fmt, ...);
 LAST_ARG_MUST_BE_NULL
 void argv_array_pushl(struct argv_array *, ...);
+void argv_array_pushv(struct argv_array *, const char **);
 void argv_array_pop(struct argv_array *);
 void argv_array_clear(struct argv_array *);
 

@@ -9,8 +9,10 @@
 #include "builtin.h"
 #include "parse-options.h"
 #include "exec_cmd.h"
+#include "run-command.h"
 
 static const char * const pull_usage[] = {
+	N_("git pull [options] [<repository> [<refspec>...]]"),
 	NULL
 };
 

@@ -18,8 +20,61 @@ static struct option pull_options[] = {
 	OPT_END()
 };
 
+/**
+ * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
+ * as a string and `refspecs` as a null-terminated array of strings. If `repo`
+ * is not provided in argv, it is set to NULL.
+ */
+static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
+		const char ***refspecs)
+{
+	if (argc > 0) {
+		*repo = *argv++;
+		argc--;
+	} else
+		*repo = NULL;
+	*refspecs = argv;
+}
+
+/**
+ * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
+ * repository and refspecs to fetch, or NULL if they are not provided.
+ */
+static int run_fetch(const char *repo, const char **refspecs)
+{
+	struct argv_array args = ARGV_ARRAY_INIT;
+	int ret;
+
+	argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
+	if (repo) {
+		argv_array_push(&args, repo);
+		argv_array_pushv(&args, refspecs);
+	} else if (*refspecs)
+		die("BUG: refspecs without repo?");
+	ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
+	argv_array_clear(&args);
+	return ret;
+}
+
+/**
+ * Runs git-merge, returning its exit status.
+ */
+static int run_merge(void)
+{
+	int ret;
+	struct argv_array args = ARGV_ARRAY_INIT;
+
+	argv_array_pushl(&args, "merge", NULL);
+	argv_array_push(&args, "FETCH_HEAD");
+	ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
+	argv_array_clear(&args);
+	return ret;
+}
+
 int cmd_pull(int argc, const char **argv, const char *prefix)
 {
+	const char *repo, **refspecs;
+
 	if (!getenv("_GIT_USE_BUILTIN_PULL")) {
 		const char *path = mkpath("%s/git-pull", git_exec_path());
 

@@ -29,5 +84,10 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 
 	argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 
-	return 0;
+	parse_repo_refspecs(argc, argv, &repo, &refspecs);
+
+	if (run_fetch(repo, refspecs))
+		return 1;
+
+	return run_merge();
 }

@@ -877,6 +877,7 @@ BUILTIN_OBJS += builtin/pack-refs.o
 BUILTIN_OBJS += builtin/patch-id.o
 BUILTIN_OBJS += builtin/prune-packed.o
 BUILTIN_OBJS += builtin/prune.o
+BUILTIN_OBJS += builtin/pull.o
 BUILTIN_OBJS += builtin/push.o
 BUILTIN_OBJS += builtin/read-tree.o
 BUILTIN_OBJS += builtin/receive-pack.o

@@ -98,6 +98,7 @@ extern int cmd_pack_redundant(int argc, const char **argv, const char *prefix);
 extern int cmd_patch_id(int argc, const char **argv, const char *prefix);
 extern int cmd_prune(int argc, const char **argv, const char *prefix);
 extern int cmd_prune_packed(int argc, const char **argv, const char *prefix);
+extern int cmd_pull(int argc, const char **argv, const char *prefix);
 extern int cmd_push(int argc, const char **argv, const char *prefix);
 extern int cmd_read_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_receive_pack(int argc, const char **argv, const char *prefix);

@@ -0,0 +1,33 @@
+/*
+ * Builtin "git pull"
+ *
+ * Based on git-pull.sh by Junio C Hamano
+ *
+ * Fetch one or more remote refs and merge it/them into the current HEAD.
+ */
+#include "cache.h"
+#include "builtin.h"
+#include "parse-options.h"
+#include "exec_cmd.h"
+
+static const char * const pull_usage[] = {
+	NULL
+};
+
+static struct option pull_options[] = {
+	OPT_END()
+};
+
+int cmd_pull(int argc, const char **argv, const char *prefix)
+{
+	if (!getenv("_GIT_USE_BUILTIN_PULL")) {
+		const char *path = mkpath("%s/git-pull", git_exec_path());
+
+		if (sane_execvp(path, (char **)argv) < 0)
+			die_errno("could not exec %s", path);
+	}
+
+	argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
+
+	return 0;
+}

@@ -445,6 +445,7 @@ static struct cmd_struct commands[] = {
 	{ "pickaxe", cmd_blame, RUN_SETUP },
 	{ "prune", cmd_prune, RUN_SETUP },
 	{ "prune-packed", cmd_prune_packed, RUN_SETUP },
+	{ "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
 	{ "push", cmd_push, RUN_SETUP },
 	{ "read-tree", cmd_read_tree, RUN_SETUP },
 	{ "receive-pack", cmd_receive_pack },

@@ -16,11 +16,35 @@ static const char * const pull_usage[] = {
 	NULL
 };
 
+/* Shared options */
+static int opt_verbosity;
+static char *opt_progress;
+
 static struct option pull_options[] = {
+	/* Shared options */
+	OPT__VERBOSITY(&opt_verbosity),
+	OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
+		N_("force progress reporting"),
+		PARSE_OPT_NOARG),
+
 	OPT_END()
 };
 
 /**
+ * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
+ */
+static void argv_push_verbosity(struct argv_array *arr)
+{
+	int verbosity;
+
+	for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
+		argv_array_push(arr, "-v");
+
+	for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
+		argv_array_push(arr, "-q");
+}
+
+/**
  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
  * is not provided in argv, it is set to NULL.

@@ -46,6 +70,12 @@ static int run_fetch(const char *repo, const char **refspecs)
 	int ret;
 
 	argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
+
+	/* Shared options */
+	argv_push_verbosity(&args);
+	if (opt_progress)
+		argv_array_push(&args, opt_progress);
+
 	if (repo) {
 		argv_array_push(&args, repo);
 		argv_array_pushv(&args, refspecs);

@@ -65,6 +95,12 @@ static int run_merge(void)
 	struct argv_array args = ARGV_ARRAY_INIT;
 
 	argv_array_pushl(&args, "merge", NULL);
+
+	/* Shared options */
+	argv_push_verbosity(&args);
+	if (opt_progress)
+		argv_array_push(&args, opt_progress);
+
 	argv_array_push(&args, "FETCH_HEAD");
 	ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 	argv_array_clear(&args);

@@ -10,6 +10,8 @@
 #include "parse-options.h"
 #include "exec_cmd.h"
 #include "run-command.h"
+#include "sha1-array.h"
+#include "remote.h"
 
 static const char * const pull_usage[] = {
 	N_("git pull [options] [<repository> [<refspec>...]]"),

@@ -165,6 +167,111 @@ static void argv_push_force(struct argv_array *arr)
 }
 
 /**
+ * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
+ * into merge_heads.
+ */
+static void get_merge_heads(struct sha1_array *merge_heads)
+{
+	const char *filename = git_path("FETCH_HEAD");
+	FILE *fp;
+	struct strbuf sb = STRBUF_INIT;
+	unsigned char sha1[GIT_SHA1_RAWSZ];
+
+	if (!(fp = fopen(filename, "r")))
+		die_errno(_("could not open '%s' for reading"), filename);
+	while (strbuf_getline(&sb, fp, '\n') != EOF) {
+		if (get_sha1_hex(sb.buf, sha1))
+			continue;  /* invalid line: does not start with SHA1 */
+		if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
+			continue;  /* ref is not-for-merge */
+		sha1_array_append(merge_heads, sha1);
+	}
+	fclose(fp);
+	strbuf_release(&sb);
+}
+
+/**
+ * Used by die_no_merge_candidates() as a for_each_remote() callback to
+ * retrieve the name of the remote if the repository only has one remote.
+ */
+static int get_only_remote(struct remote *remote, void *cb_data)
+{
+	const char **remote_name = cb_data;
+
+	if (*remote_name)
+		return -1;
+
+	*remote_name = remote->name;
+	return 0;
+}
+
+/**
+ * Dies with the appropriate reason for why there are no merge candidates:
+ *
+ * 1. We fetched from a specific remote, and a refspec was given, but it ended
+ *    up not fetching anything. This is usually because the user provided a
+ *    wildcard refspec which had no matches on the remote end.
+ *
+ * 2. We fetched from a non-default remote, but didn't specify a branch to
+ *    merge. We can't use the configured one because it applies to the default
+ *    remote, thus the user must specify the branches to merge.
+ *
+ * 3. We fetched from the branch's or repo's default remote, but:
+ *
+ *    a. We are not on a branch, so there will never be a configured branch to
+ *       merge with.
+ *
+ *    b. We are on a branch, but there is no configured branch to merge with.
+ *
+ * 4. We fetched from the branch's or repo's default remote, but the configured
+ *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
+ *    part of the configured fetch refspec.)
+ */
+static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
+{
+	struct branch *curr_branch = branch_get("HEAD");
+	const char *remote = curr_branch ? curr_branch->remote_name : NULL;
+
+	if (*refspecs) {
+		fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
+		fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
+					"matches on the remote end."));
+	} else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
+		fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
+			"a branch. Because this is not the default configured remote\n"
+			"for your current branch, you must specify a branch on the command line."),
+			repo);
+	} else if (!curr_branch) {
+		fprintf_ln(stderr, _("You are not currently on a branch."));
+		fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
+		fprintf_ln(stderr, _("See git-pull(1) for details."));
+		fprintf(stderr, "\n");
+		fprintf_ln(stderr, "    git pull <remote> <branch>");
+		fprintf(stderr, "\n");
+	} else if (!curr_branch->merge_nr) {
+		const char *remote_name = NULL;
+
+		if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
+			remote_name = "<remote>";
+
+		fprintf_ln(stderr, _("There is no tracking information for the current branch."));
+		fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
+		fprintf_ln(stderr, _("See git-pull(1) for details."));
+		fprintf(stderr, "\n");
+		fprintf_ln(stderr, "    git pull <remote> <branch>");
+		fprintf(stderr, "\n");
+		fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:\n"
+				"\n"
+				"    git branch --set-upstream-to=%s/<branch> %s\n"),
+				remote_name, curr_branch->name);
+	} else
+		fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
+			"from the remote, but no such ref was fetched."),
+			*curr_branch->merge_name);
+	exit(1);
+}
+
+/**
  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
  * is not provided in argv, it is set to NULL.

@@ -277,6 +384,7 @@ static int run_merge(void)
 int cmd_pull(int argc, const char **argv, const char *prefix)
 {
 	const char *repo, **refspecs;
+	struct sha1_array merge_heads = SHA1_ARRAY_INIT;
 
 	if (!getenv("_GIT_USE_BUILTIN_PULL")) {
 		const char *path = mkpath("%s/git-pull", git_exec_path());

@@ -295,5 +403,10 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (opt_dry_run)
 		return 0;
 
+	get_merge_heads(&merge_heads);
+
+	if (!merge_heads.nr)
+		die_no_merge_candidates(repo, refspecs);
+
 	return run_merge();
 }

@@ -32,6 +32,21 @@ static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
 static char *opt_gpg_sign;
 
+/* Options passed to git-fetch */
+static char *opt_all;
+static char *opt_append;
+static char *opt_upload_pack;
+static int opt_force;
+static char *opt_tags;
+static char *opt_prune;
+static char *opt_recurse_submodules;
+static int opt_dry_run;
+static char *opt_keep;
+static char *opt_depth;
+static char *opt_unshallow;
+static char *opt_update_shallow;
+static char *opt_refmap;
+
 static struct option pull_options[] = {
 	/* Shared options */
 	OPT__VERBOSITY(&opt_verbosity),

@@ -82,6 +97,46 @@ static struct option pull_options[] = {
 		N_("GPG sign commit"),
 		PARSE_OPT_OPTARG),
 
+	/* Options passed to git-fetch */
+	OPT_GROUP(N_("Options related to fetching")),
+	OPT_PASSTHRU(0, "all", &opt_all, 0,
+		N_("fetch from all remotes"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU('a', "append", &opt_append, 0,
+		N_("append to .git/FETCH_HEAD instead of overwriting"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
+		N_("path to upload pack on remote end"),
+		0),
+	OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
+	OPT_PASSTHRU('t', "tags", &opt_tags, 0,
+		N_("fetch all tags and associated objects"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU('p', "prune", &opt_prune, 0,
+		N_("prune remote-tracking branches no longer on remote"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU(0, "recurse-submodules", &opt_recurse_submodules,
+		N_("on-demand"),
+		N_("control recursive fetching of submodules"),
+		PARSE_OPT_OPTARG),
+	OPT_BOOL(0, "dry-run", &opt_dry_run,
+		N_("dry run")),
+	OPT_PASSTHRU('k', "keep", &opt_keep, 0,
+		N_("keep downloaded pack"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
+		N_("deepen history of shallow clone"),
+		0),
+	OPT_PASSTHRU(0, "unshallow", &opt_unshallow, 0,
+		N_("convert to a complete repository"),
+		PARSE_OPT_NONEG | PARSE_OPT_NOARG),
+	OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, 0,
+		N_("accept refs that update .git/shallow"),
+		PARSE_OPT_NOARG),
+	OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
+		N_("specify fetch refmap"),
+		PARSE_OPT_NONEG),
+
 	OPT_END()
 };
 

@@ -100,6 +155,16 @@ static void argv_push_verbosity(struct argv_array *arr)
 }
 
 /**
+ * Pushes "-f" switches into arr to match the opt_force level.
+ */
+static void argv_push_force(struct argv_array *arr)
+{
+	int force = opt_force;
+	while (force-- > 0)
+		argv_array_push(arr, "-f");
+}
+
+/**
  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
  * is not provided in argv, it is set to NULL.

@@ -131,6 +196,33 @@ static int run_fetch(const char *repo, const char **refspecs)
 	if (opt_progress)
 		argv_array_push(&args, opt_progress);
 
+	/* Options passed to git-fetch */
+	if (opt_all)
+		argv_array_push(&args, opt_all);
+	if (opt_append)
+		argv_array_push(&args, opt_append);
+	if (opt_upload_pack)
+		argv_array_push(&args, opt_upload_pack);
+	argv_push_force(&args);
+	if (opt_tags)
+		argv_array_push(&args, opt_tags);
+	if (opt_prune)
+		argv_array_push(&args, opt_prune);
+	if (opt_recurse_submodules)
+		argv_array_push(&args, opt_recurse_submodules);
+	if (opt_dry_run)
+		argv_array_push(&args, "--dry-run");
+	if (opt_keep)
+		argv_array_push(&args, opt_keep);
+	if (opt_depth)
+		argv_array_push(&args, opt_depth);
+	if (opt_unshallow)
+		argv_array_push(&args, opt_unshallow);
+	if (opt_update_shallow)
+		argv_array_push(&args, opt_update_shallow);
+	if (opt_refmap)
+		argv_array_push(&args, opt_refmap);
+
 	if (repo) {
 		argv_array_push(&args, repo);
 		argv_array_pushv(&args, refspecs);

@@ -200,5 +292,8 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (run_fetch(repo, refspecs))
 		return 1;
 
+	if (opt_dry_run)
+		return 0;
+
 	return run_merge();
 }

@@ -96,6 +96,14 @@ void NORETURN die_resolve_conflict(const char *me)
 	die("Exiting because of an unresolved conflict.");
 }
 
+void NORETURN die_conclude_merge(void)
+{
+	error(_("You have not concluded your merge (MERGE_HEAD exists)."));
+	if (advice_resolve_conflict)
+		advise(_("Please, commit your changes before you can merge."));
+	die(_("Exiting because of unfinished merge."));
+}
+
 void detach_advice(const char *new_name)
 {
 	const char fmt[] =

@@ -24,6 +24,7 @@ __attribute__((format (printf, 1, 2)))
 void advise(const char *advice, ...);
 int error_resolve_conflict(const char *me);
 extern void NORETURN die_resolve_conflict(const char *me);
+void NORETURN die_conclude_merge(void);
 void detach_advice(const char *new_name);
 
 #endif /* ADVICE_H */

@@ -12,6 +12,7 @@
 #include "run-command.h"
 #include "sha1-array.h"
 #include "remote.h"
+#include "dir.h"
 
 static const char * const pull_usage[] = {
 	N_("git pull [options] [<repository> [<refspec>...]]"),

@@ -426,6 +427,14 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (!opt_ff)
 		opt_ff = xstrdup_or_null(config_get_ff());
 
+	git_config(git_default_config, NULL);
+
+	if (read_cache_unmerged())
+		die_resolve_conflict("Pull");
+
+	if (file_exists(git_path("MERGE_HEAD")))
+		die_conclude_merge();
+
 	if (run_fetch(repo, refspecs))
 		return 1;
 

@@ -169,6 +169,25 @@ static void argv_push_force(struct argv_array *arr)
 }
 
 /**
+ * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
+ */
+static void set_reflog_message(int argc, const char **argv)
+{
+	int i;
+	struct strbuf msg = STRBUF_INIT;
+
+	for (i = 0; i < argc; i++) {
+		if (i)
+			strbuf_addch(&msg, ' ');
+		strbuf_addstr(&msg, argv[i]);
+	}
+
+	setenv("GIT_REFLOG_ACTION", msg.buf, 0);
+
+	strbuf_release(&msg);
+}
+
+/**
  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an

@@ -443,6 +462,9 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 			die_errno("could not exec %s", path);
 	}
 
+	if (!getenv("GIT_REFLOG_ACTION"))
+		set_reflog_message(argc, argv);
+
 	argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 
 	parse_repo_refspecs(argc, argv, &repo, &refspecs);

@@ -167,6 +167,32 @@ static void argv_push_force(struct argv_array *arr)
 }
 
 /**
+ * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
+ * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
+ * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
+ * error.
+ */
+static const char *config_get_ff(void)
+{
+	const char *value;
+
+	if (git_config_get_value("pull.ff", &value))
+		return NULL;
+
+	switch (git_config_maybe_bool("pull.ff", value)) {
+	case 0:
+		return "--no-ff";
+	case 1:
+		return "--ff";
+	}
+
+	if (!strcmp(value, "only"))
+		return "--ff-only";
+
+	die(_("Invalid value for pull.ff: %s"), value);
+}
+
+/**
  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
  * into merge_heads.
  */

@@ -397,6 +423,9 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 
 	parse_repo_refspecs(argc, argv, &repo, &refspecs);
 
+	if (!opt_ff)
+		opt_ff = xstrdup_or_null(config_get_ff());
+
 	if (run_fetch(repo, refspecs))
 		return 1;
 

@@ -13,6 +13,7 @@
 #include "sha1-array.h"
 #include "remote.h"
 #include "dir.h"
+#include "refs.h"
 
 static const char * const pull_usage[] = {
 	N_("git pull [options] [<repository> [<refspec>...]]"),

@@ -368,6 +369,27 @@ static int run_fetch(const char *repo, const char **refspecs)
 }
 
 /**
+ * "Pulls into void" by branching off merge_head.
+ */
+static int pull_into_void(const unsigned char *merge_head,
+		const unsigned char *curr_head)
+{
+	/*
+	 * Two-way merge: we treat the index as based on an empty tree,
+	 * and try to fast-forward to HEAD. This ensures we will not lose
+	 * index/worktree changes that the user already made on the unborn
+	 * branch.
+	 */
+	if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0))
+		return 1;
+
+	if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
+		return 1;
+
+	return 0;
+}
+
+/**
  * Runs git-merge, returning its exit status.
  */
 static int run_merge(void)

@@ -476,5 +498,10 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (!merge_heads.nr)
 		die_no_merge_candidates(repo, refspecs);
 
-	return run_merge();
+	if (is_null_sha1(orig_head)) {
+		if (merge_heads.nr > 1)
+			die(_("Cannot merge multiple branches into empty head."));
+		return pull_into_void(*merge_heads.sha1, curr_head);
+	} else
+		return run_merge();
 }

@@ -412,6 +412,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 {
 	const char *repo, **refspecs;
 	struct sha1_array merge_heads = SHA1_ARRAY_INIT;
+	unsigned char orig_head[GIT_SHA1_RAWSZ], curr_head[GIT_SHA1_RAWSZ];
 
 	if (!getenv("_GIT_USE_BUILTIN_PULL")) {
 		const char *path = mkpath("%s/git-pull", git_exec_path());

@@ -435,12 +436,41 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (file_exists(git_path("MERGE_HEAD")))
 		die_conclude_merge();
 
+	if (get_sha1("HEAD", orig_head))
+		hashclr(orig_head);
+
 	if (run_fetch(repo, refspecs))
 		return 1;
 
 	if (opt_dry_run)
 		return 0;
 
+	if (get_sha1("HEAD", curr_head))
+		hashclr(curr_head);
+
+	if (!is_null_sha1(orig_head) && !is_null_sha1(curr_head) &&
+			hashcmp(orig_head, curr_head)) {
+		/*
+		 * The fetch involved updating the current branch.
+		 *
+		 * The working tree and the index file are still based on
+		 * orig_head commit, but we are merging into curr_head.
+		 * Update the working tree to match curr_head.
+		 */
+
+		warning(_("fetch updated the current branch head.\n"
+			"fast-forwarding your working tree from\n"
+			"commit %s."), sha1_to_hex(orig_head));
+
+		if (checkout_fast_forward(orig_head, curr_head, 0))
+			die(_("Cannot fast-forward your working tree.\n"
+				"After making sure that you saved anything precious from\n"
+				"$ git diff %s\n"
+				"output, run\n"
+				"$ git reset --hard\n"
+				"to recover."), sha1_to_hex(orig_head));
+	}
+
 	get_merge_heads(&merge_heads);
 
 	if (!merge_heads.nr)